CVE-2015-2987 in Type74 ED
Summary
by MITRE
Type74 ED before 4.0 misuses 128-bit ECB encryption for small files, which makes it easier for attackers to obtain plaintext data via differential cryptanalysis of a file with an original length smaller than 128 bits.
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Analysis
by VulDB Data Team • 11/13/2017
The vulnerability described in CVE-2015-2987 affects Type74 ED versions prior to 4.0 and represents a significant cryptographic weakness in how the system handles encryption for small files. This issue stems from the improper implementation of encryption algorithms where the system employs 128-bit Electronic Codebook (ECB) mode for files smaller than 128 bits in length. The fundamental problem lies in ECB mode's deterministic nature, which means identical plaintext blocks will always produce identical ciphertext blocks, creating patterns that can be exploited by adversaries. This cryptographic flaw directly violates established security principles and creates predictable encryption outcomes that undermine the confidentiality guarantees that encryption is designed to provide.
The technical exploitation of this vulnerability occurs through differential cryptanalysis techniques that leverage the predictable nature of ECB encryption when applied to small data sets. When files smaller than 128 bits are encrypted using ECB mode, the encryption process fails to provide adequate diffusion of the plaintext data across the ciphertext, allowing attackers to analyze multiple encrypted versions of similar files and potentially reconstruct the original plaintext content. This weakness is particularly dangerous because it does not require advanced cryptographic knowledge or significant computational resources to exploit, making it accessible to a wide range of threat actors. The vulnerability specifically targets the encryption implementation rather than the broader system architecture, making it a targeted cryptographic flaw that can be systematically analyzed and exploited.
The operational impact of this vulnerability extends beyond simple data confidentiality breaches as it creates a persistent risk for any system utilizing Type74 ED versions before 4.0 for file encryption. Organizations that store sensitive data using this encryption method become vulnerable to pattern recognition attacks that can reveal information about file contents, potentially exposing intellectual property, personal data, or other confidential information. The vulnerability affects the core encryption functionality and can compromise entire data repositories if multiple small files are encrypted using the same key. This creates cascading security risks where a single weak encryption implementation can expose large volumes of sensitive information across various file types and organizational domains.
From a cybersecurity framework perspective, this vulnerability aligns with CWE-327 which addresses the use of insecure encryption algorithms and improper implementation of cryptographic functions. The weakness also maps to ATT&CK technique T1552.004 which involves the exploitation of weak encryption or cryptographic implementations. The recommended mitigations include upgrading to Type74 ED version 4.0 or later where the encryption implementation has been properly addressed, implementing additional layers of security such as authenticated encryption modes, and conducting thorough cryptographic assessments of all encryption implementations. Organizations should also consider implementing key rotation policies and ensuring that encryption algorithms are properly validated against industry standards such as those defined in NIST SP 800-38A for block cipher modes of operation. The vulnerability demonstrates the critical importance of proper cryptographic implementation and the dangers of using encryption modes that do not provide adequate diffusion properties for all data sizes.